In vivo integrated photoacoustic and confocal microscopy of hemoglobin oxygen saturation and oxygen partial pressure

We developed dual-modality microscope integrating photoacoustic microscopy (PAM) and fluorescence confocal microscopy (FCM) to noninvasively image hemoglobin oxygen saturation (sO(2)) and oxygen partial pressure (pO(2)) in vivo in single blood vessels with high spatial resolution. While PAM measures sO(2) by imaging hemoglobin optical absorption at two wavelengths, FCM quantifies pO(2) using phosphorescence quenching. The variations of sO(2) and pO(2) values in multiple orders of vessel branches under hyperoxic (100% oxygen) and normoxic (21% oxygen) conditions correlate well with the oxygen-hemoglobin dissociation curve. In addition, the total concentration of hemoglobin is imaged by PAM at an isosbestic wavelength. (C) 2011 Optical Society of America